1. Field of the Invention
The present invention relates to an image sensor package structure and, more particularly, to an image sensor package structure and an image sensing module capable of reducing the package area.
2. Description of Related Art
As shown in FIG. 1, a conventional CMOS image sensor package structure comprises a substrate 10, a frame 20, an image sensing chip 30 and a light transparent glass 40. Several metallization traces 11 are formed on the surface of the substrate 10. The frame 20 is adhered to the substrate 10 using a first glue layer 12. The image sensing chip 30 is adhered to the substrate 10. The image sensing chip 30 has a sensing region 31. The image sensing chip 30 uses metal wires 32 to connect the metallization traces 11 on the surface of the substrate 10 by means of wire bonding, thereby achieving electric connection between the image sensing chip 30 and the substrate 10. The light transparent glass 40 seals and covers on the substrate 10 using a second glue layer 13. This package structure can isolate external particles to make the CMOS image sensor truly sense the external environment.
The above package structure, however, has many limitations in the package area and volume, and is unsuitable to portable products. First, when wire bonding is performed, because there is a drop height between the image sensing chip 30 and the substrate 10, a corresponding wire bonding distance S1 is required. Moreover, because the frame 20 is first adhered onto the substrate 10 in the conventional packaging procedure, it is necessary to keep a distance S2 between the frame 20 and the metallization traces 11 on the substrate 10 to prevent the capillary from touching the frame 20. Besides, because an action of removing particles is performed before sealing the light transparent glass 40, the distance between the image sensing chip 30 and the frame 20 cannot be too small. Otherwise, the particles between the image sensing chip 30 and the frame 20 cannot be easily removed.
Some image sensor packaging methods capable of reducing the package volume have been developed later. For instance, in one packaging process, the image sensing chip is first mounted on the substrate, and the frame is then adhered onto the substrate to save the package size. However, when assembling with a common lens set, a lens base is still directly mounted outside the frame. Therefore, the relative volume cannot be shrunk. In another package structure, grooves are provided at the inside and outside of the top of the frame to install the light transparent glass and a lens base. But the frame cannot be easily manufactured during injection molding. Moreover, in order to accommodate the lens base, extra space outside the frame is wasted.
In yet another package structure, the top of the frame extends horizontally toward the image sensing chip. Two grooves are designed on the extending portion to bear a lens base and the light transparent glass. Although the size of the lens set of this package structure can be smaller than that of the frame, the requirement for the package accuracy is high so that precision production machines are required. Moreover, because the connection position of the light transparent glass and the groove of the frame is very close to the sensing region of the image sensing chip, glue material may easily flow to the surface of the image sensing chip during the gluing process to affect the production yield and quality.